Magnetic disks and disk drives are conventionally employed for storing data in magnetizable form. Preferably, one or more disks are rotated on a central axis in combination with data transducing heads positioned in close proximity to the recording surfaces of the disks and moved generally radially with respect thereto. Magnetic disks are usually housed in a magnetic disk unit in a stationary state with a magnetic head having a specific load elastically in contact with and pressed against the surface of the disk. Data are written onto and read from a rapidly rotating recording disk by means of a magnetic head transducer assembly that flies closely over the surface of the disk. Preferably, each face of each disk will have its own independent head.
A disk recording medium is shown in FIG. 1. Even though FIG. 1 shows sequential layers on one side of the non-magnetic substrate 10, it is known to sputter deposit sequential layers on both sides of the non-magnetic substrate.
Adverting to FIG. 1, a sub-seed layer 11 is deposited on substrate 10, e.g., a glass or glass-ceramic, Al or AlMg substrate. Subsequently, a seed layer 12 is deposited on the sub-seed layer 11. Then, an underlayer 13 is sputter deposited on the seed layer 12. An intermediate or flash layer 14 is then sputter deposited on underlayer 13. Magnetic layer 15 is then sputter deposited on the intermediate layer, e.g., CoCrPtTa. A protective covering overcoat 16 is then sputter deposited on the magnetic layer 15. A lubricant topcoat (not shown in FIG. 1 for illustrative convenience) is deposited on the protective covering overcoat 16.
The disk is finely balanced and finished to microscopic tolerances. Take the smoothness of its surface, for example. The drive head rides a cushion of air at microscopic distances above the surface of the disk. So, the surface cannot be too smooth, or the drive lead will end up sticking to the disk, and it cannot be too rough either, or the head will end up getting caught in the microscopic bumps on the surface.
It is considered desirable during reading and recording operations to maintain each transducer head as close to its associated recording surface as possible, i.e., to minimize the flying height of the head. This objective becomes particularly significant as the areal recording density increases. The areal density (Mbits/in2) is the recording density per unit area and is equal to the track density (TPI) in terms of tracks per inch times the linear density (BPI) in terms of bits per inch.
In recent years, considerable effort has been expended to achieve high areal recording density. In particular, the requirement to further reduce the flying height of the head imposed by increasingly higher recording density and capacity renders the disk drive particularly vulnerable to head crash due to accidental glide hits of the head and media. To avoid glide hits, a smooth defect-free surface of data zone is desired. The direct result of these demands is tending towards low yield due to less defect tolerance at the surface of the media. Thus, it is desired to arrive at an improved mechanism for burnishing/polishing the surface of the discs to produce defect-free surface.